1 files changed, 107 insertions, 0 deletions
diff --git a/src/main/javassist/convert/TransformBefore.java b/src/main/javassist/convert/TransformBefore.java
new file mode 100644
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--- /dev/null
+++ b/src/main/javassist/convert/TransformBefore.java
@@ -0,0 +1,107 @@
+/*
+ * Javassist, a Java-bytecode translator toolkit.
+ * Copyright (C) 1999-2007 Shigeru Chiba. All Rights Reserved.
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License.  Alternatively, the contents of this file may be used under
+ * the terms of the GNU Lesser General Public License Version 2.1 or later.
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ */
+
+package javassist.convert;
+
+import javassist.CtClass;
+import javassist.CtMethod;
+import javassist.NotFoundException;
+import javassist.bytecode.*;
+
+public class TransformBefore extends TransformCall {
+    protected CtClass[] parameterTypes;
+    protected int locals;
+    protected int maxLocals;
+    protected byte[] saveCode, loadCode;
+
+    public TransformBefore(Transformer next,
+                           CtMethod origMethod, CtMethod beforeMethod)
+        throws NotFoundException
+    {
+        super(next, origMethod, beforeMethod);
+
+        // override
+        methodDescriptor = origMethod.getMethodInfo2().getDescriptor();
+
+        parameterTypes = origMethod.getParameterTypes();
+        locals = 0;
+        maxLocals = 0;
+        saveCode = loadCode = null;
+    }
+
+    public void initialize(ConstPool cp, CodeAttribute attr) {
+        super.initialize(cp, attr);
+        locals = 0;
+        maxLocals = attr.getMaxLocals();
+        saveCode = loadCode = null;
+    }
+
+    protected int match(int c, int pos, CodeIterator iterator,
+                        int typedesc, ConstPool cp) throws BadBytecode
+    {
+        if (newIndex == 0) {
+            String desc = Descriptor.ofParameters(parameterTypes) + 'V';
+            desc = Descriptor.insertParameter(classname, desc);
+            int nt = cp.addNameAndTypeInfo(newMethodname, desc);
+            int ci = cp.addClassInfo(newClassname);
+            newIndex = cp.addMethodrefInfo(ci, nt);
+            constPool = cp;
+        }
+
+        if (saveCode == null)
+            makeCode(parameterTypes, cp);
+
+        return match2(pos, iterator);
+    }
+
+    protected int match2(int pos, CodeIterator iterator) throws BadBytecode {
+        iterator.move(pos);
+        iterator.insert(saveCode);
+        iterator.insert(loadCode);
+        int p = iterator.insertGap(3);
+        iterator.writeByte(INVOKESTATIC, p);
+        iterator.write16bit(newIndex, p + 1);
+        iterator.insert(loadCode);
+        return iterator.next();
+    }
+
+    public int extraLocals() { return locals; }
+
+    protected void makeCode(CtClass[] paramTypes, ConstPool cp) {
+        Bytecode save = new Bytecode(cp, 0, 0);
+        Bytecode load = new Bytecode(cp, 0, 0);
+
+        int var = maxLocals;
+        int len = (paramTypes == null) ? 0 : paramTypes.length;
+        load.addAload(var);
+        makeCode2(save, load, 0, len, paramTypes, var + 1);
+        save.addAstore(var);
+
+        saveCode = save.get();
+        loadCode = load.get();
+    }
+
+    private void makeCode2(Bytecode save, Bytecode load,
+                           int i, int n, CtClass[] paramTypes, int var)
+    {
+        if (i < n) {
+            int size = load.addLoad(var, paramTypes[i]);
+            makeCode2(save, load, i + 1, n, paramTypes, var + size);
+            save.addStore(var, paramTypes[i]);
+        }
+        else
+            locals = var - maxLocals;
+    }
+}